The long term objective of this proposal is to understand the organization of basement membranes and their role in normal and pathological states. Basement membranes are complex extracellular matrices that are involved in tissue organization, embryogenesis, cell adhesion, filtration and protection. There are alterations in basement membrane structures in many pathological states such as diabetes mellitus, cancer, bullous pemphigoid, asthma, glomeruluo-nephritis of varied origin and several of the autoimmune diseases. The specific objectives of this proposal are two fold: (a) basement membrane organization will be studied with a model matrix produced in cell culture by mouse endoderm cells and (b) the regulation of the genes for laminin and entactin, two basement membrane components will be explored. The techniques that will be employed include the construction of hybridoma cells to generate specific probes for examining basement membrane organization, peptide isolation and sequencing, isolation and characterization of DNA sequences that code for the genes of laminin and entactin, and induction of embryonal carcinoma F9 cells with retinoic acid and dibutyryl cyclic AMP to study the expression of laminin and entactin.